net/igmpproxy: Update to 0.3

igmpproxy update to 0.3, mostly fixing previous FreeBSD build issues.

MAX_IF patch kept and raised further to retain operation when many addresses are found in the system. (On OPNsense/pfSense 40 addresses can be too low.)

PR: 252857
Submitted by: Franco Fichtner <franco@opnsense.org> (maintainer)